In a majority of alcoholic indiviuals the proportion of hemoglobin in the form of minor hemoglobins is significantly greater than normal. In accord with this finding, hemolysates from alcoholic men and women were found to contain a novel form of hemoglobin (hemoglobin Alalc having the following characteristics: (1) It co-chromatographs with hemoglobin Alc on the cationic exchange resin Biorex 70. (2) It is not bound, as is hemoglobin Alc, by aminophenylboronated agarose and can therefore be separated from it. (3) It does not give a positive reaction for glycosylated hemoglobin by the Fluckiger-Winterhalter test. A form of hemoglobin having properties similar to hemoglobin Alalc and that contained 1 molar equivalent of acetaldehyde per mole of hemoglobin was found in hemolysates prepared from human erythrocytes that had been incubated with 175 MuM (1-3H) acetaldehyde. This and other evidence indicate that hemoglobin Alalc is post-translationally modified hemoglobin A and that it is formed by addition to hemoglobin A of a functional group derived from metabolically produced acetaldehyde. The chief objectives of this project, therefore, are to elucidate the structure and site of attachment of the functional group that transforms hemoglobin A to hemoglobin Alalc and to elucidate the structure and site of attachment of the acetaldehyde-derived modifying group in hemoglobin Alald. To accomplish these objectives the approaches and procedures will be applied that succeeded in establishing the pathway and mechanism of formation of hemoglobin Alc. Should hemoglobins Alalc and Alald prove to be identical, thus directly relating formation of hemoglobin Alalc to alcohol consumption, it may be possible to use that relationship to investigate the development of alcoholism and alcohol-related disorders and to use measurements of hemoglobin Alalc to screen for covert alcoholism and alcohol abuse. For these reasons this project will also concern itself with the development of a specific and simple method for the determination of hemoglobin Alalc.